A 1200 ka Stable Isotope Record From the Center of the Badain Jaran Desert, Northwestern China: Implications for the Variation and Interplay of the Westerlies and the Asian Summer Monsoon

Abstract The variation and interplay of westerlies and the Asian summer monsoon (ASM) are important for understanding climate change in the Northern Hemisphere. Yet their spatial and temporal evolution is still debatable. Here, we present a stable isotopic record from the center of the Badain Jaran Desert, in Northwestern China, which records the variations and interplay of the two climate systems during the past 1200 ka. The results indicate that the westerlies dominated the Badain Jaran area at least from 1200 to 600 ka, and possibly earlier. Associated with ASM enhancement since 600 ka, the westerlies and ASM alternatively dominated the regional warm season precipitation during glacial‐interglacial cycles, respectively. Meanwhile, the δ18Ocarb of the Badain Jaran area showed high‐frequency fluctuations which may reveal the joint impact of ASM and westerlies on regional hydrology after 450 ka. Affected by the westerlies and ASM changes, the C4 plants stepwise expanded at 600, 450, and 300 ka. These stepwise variations of westerlies and ASM are response to the global climate change which significantly influenced the ASM at 600 and 450 ka, and westerlies at 300 ka, respectively. In addition, the uplift of the Pamir‐Tibetan Plateau during the middle Pleistocene also exerts a profound effect on westerlies and ASM pattern across the East Asia on a long‐term time scale.